The present invention relates to an improvement in a remotely actuated telephone subscriber's service connection block. More particularly, this invention relates to a remotely actuated telephone instrument connection block having a circuit for locking out the instrument in response to a remotely sent control signal.
Telephone instrument connection blocks which provide finite test conditions and signals emulative of a field troubleshooter's tests in response from control signals sent remotely from a telephone exchange central office have been adopted on a widespread basis throughout most of the countries of the world, principally because of the labor savings such devices provide. One such block which has achieved widespread adoption and use is disclosed in my U.S. Pat. No. 4,169,220, entitled "Telphone Instrument Connection Block With Remotely Actuated Line Test". The disclosure of my said prior patent is hereby expressly incorporated by reference as part of the present disclosure.
In the use of my prior connection block it has been discovered that there are situations when the telephone company or agency may wish to disconnect a subscriber effectively from the telephone system. Usually, those situations are related to nonpayment of telephone tolls and charges, but they may be related to customer services such as disconnection during vacations or extended absences at the customer's request, so that unauthorized calls may not be made. This need has arisen in the case of vacation homes where phone service is not required or desired on a year-round basis. Another situation requiring a remote lockout arises when a subscriber's equipment may be the source of trouble or hazard to the telephone plant in place (i.e. telephone lines and central office equipment to which the lines are connected). With the increasing widespread use of customer owned and supplied telephone instruments the liklihood of incompatiblity and harm to the telephone system has increased.
Lockout devices are known in the prior art. However, the lockout devices currently known and used have an inherent drawback in that the latching circuitry which effectuates the lockout is constantly connected to the telephone tip and ring wire pair. This constant connection makes such circuits vulnerable to false operation in response to spurious, unintended signals which often become induced into the telephone system. For example, there exists a strong liklihood that a central office repair technician or cable splicer may inadvertently apply an operating potential to many lines at once, incident to repair or testing activities. With the prior art devices, they will respond to such an erroneous signal by latching out all of the customers whose lines were contacted. Consequently, those prior lockout devices constituted a potential cause of trouble and difficulty themselves. A need has arisen, therefore, for a lockout circuit which is essentially inoperative during normal line operation conditions and which becomes operative only during a test sequence.